PORT ANGELES — If you needed another reason to abhor ticks, a recent study found the spider-like parasites in Clallam County have the potential to spread Lyme disease.

Four of the 19 Ixodes pacificus Western black-legged ticks collected in Clallam County between August 2012 and July 2013 tested positive for Borrelia burgdorferi, the bacteria that causes Lyme disease, in a statewide tick survey.

“This is a potential health threat,” said Dr. Tom Locke, public health officer for Clallam and Jefferson counties.

“It’s not a known health threat yet.”

While there have been no confirmed cases of Lyme disease in Clallam or Jefferson counties, Locke is urging the public to use insect repellent and check for tick bites after hiking in the woods.

If you find a tick, use tweezers and pull slowly so you don’t leave the head behind, he said.

In the coming months, health officials will place warning signs about ticks and tick-borne diseases at popular trailheads, particularly around Lake Crescent and Indian Valley, where all of the Borrelia-carrying ticks on the North Olympic Peninsula were found.

Locke is also urging health care providers to be vigilant about the symptoms of Lyme disease, which include fever, headache, fatigue and a “bulls eye” rash that spreads around the site of a tick bite.

If left untreated, Lyme disease can spread to joints, heart and nervous system, according to the Centers for Disease Control and Prevention.

Locke, who briefed Olympic Medical Center medical staff and the Clallam County Board of Health about tick-borne diseases this month, said the risk of catching Lyme disease is “very low” and “probably very localized” to the Lake Crescent-Indian Valley area.

All four of the ticks that tested positive for Borrelia burgdorferi were collected on the ridge north of Indian Valley.

Reports of tick bites are common on the Spruce Railroad Trail on the north shore of Lake Crescent, Locke said.

“The way I’m responding to this is really asking for a higher level of suspicion among medical providers to do what we call active surveillance, to understand that there’s at least a possibility of (Lyme disease) within the county,” Locke said.

Since the statewide tick surveillance program began three years ago, Clallam and Mason were the only counties where Borrelia burgdorferi was discovered in ticks.

Western black legged ticks collected in Jefferson County did not contain the agent for Lyme disease.

Mason County had two of the 13 confirmed cases of Lyme disease among Washington state residents who had no history of travel between 2004 and 2012.

“Some had tick bite history and some did not,” Locke said of the confirmed cases.

“We’ve known that it’s been in the state at a very low level.”

Ticks get Borrelia by feeding on infected animals, which on the Peninsula are probably woodrats.

“On the East Coast, it’s in deer as well,” Locke said.

“(Borrelia) has what’s called a reservoir host. A species gets infected with it, and then ticks feed on that species, and in the course of their life cycle they feed on other things, including sometimes us.”

To collect ticks for the three-year surveillance program, federal and state wildlife officials dragged flannel sheets over grass the forest.

“The ticks tend to jump out and adhere to the flannel sheet and they periodically check and see if they’ve got any ticks,” Locke said.

The ticks were placed in plastic vials and sent to the University of Massachusetts for testing.

“We’re hoping to do more tick sampling,” Locke said.

Locke said it’s best to avoid ticks by using insect repellent and wearing long pants.

“If you find a tick on you and it’s been attached for less than 24 hours and you remove it, your chance of getting Lyme disease is dramatically reduced to almost zero,” Locke said.

“Also, if you’re bit by a tick and you don’t discover it, you can watch yourself for the signs and symptoms, or you can seek medical attention.”